Rock-drill.



1 J. M. 61 J. L. HOLMAN.

ROCK DRILL.

APPLICATION 111.1111 mm: 22, 1911.

1 1,029,294, Patente d June 11,1912.

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JAMES MINERS I-IOLMAN AND JOHN LEONARD I'IOLMAN, OF CAMBORNE, ENGLAND.

ROCK-DRILL.

To all whom it may concern:

Be it known that we, J AMES MINERs Hon MAN and JOHN LEONARD HoLMAN, both subjects of the King of Great Britain, residing at Camborne, Cornwall, England, have invented new and useful Improvements in Rock-Drills, of which the following is a specification.

Our invention relates to rock-drills of the type wherein the distributing valve is operated through the medium of a pivoted rocker which engages with the said valve, and which receives its motion from inclines or tappets upon the piston.

In drills of this class as hitherto constructed it has been usual to so construct the rocker that the ends thereof extend into the cylinder and are directly acted upon by tappets or by the piston during the reciprocation of the latter.

The object of our invention is to improve upon this construction, and to this end the ends of the rocker, instead of projecting into the cylinder, are made somewhat shorter than heretofore and balls are interposed between these ends and the piston, the said balls resting upon seats, the balls projecting so far into the cylinder that they will be pushed back by the piston or the tappets during the reciprocation.

Our invention will be readily understood by reference to the accompanying drawing,

which is a sectional view of a portion of a roclcdrill having our improvements applied to it.

a indicates the working cylinder, Z) the piston reciprocated therein, and which is formed with a recess as indicated at 0 in a wellknown manner, (Z the air chamber,

Specification of Letters Patent.

Application filed June 22, 1911.

Serial No. 634,687.

with the said tappet, the said balls being carried in bushes or sockets h adjacent to the arms of the rocker, in such a manner that they project into the path of the piston, so that, as the latter reciprocates, the requisite rocking movement will be imparted to the rocker.

With this construction it will be understood that the wear which takes place between the points of contact is much less than hitherto, owing to the fact that the balls 9, 9 will rotate and present all parts of their surfaces at one time or another to the action of the tappets or inclines on the piston.

It will also be seen that the bushes or sockets it have their apertures reduced at their inner ends to hold the balls from projecting more than a slight distance into the cylinder and thereby hold them out of contact with the reduced or recessed portion of the piston. The balls 9 9 therefore only come into con tact with a portion of the inclined shoulders 7) b of the piston at each end of the piston stroke, thus greatly reducing the Wear on the piston and balls.

Claims:

1. In a rock drill, the combination with a working cylinder, and a piston therein provided with a recessed portion, and inclined actuating shoulders, adjacentto said recessed portion, of a distributing valve forsaid cylinder, a pivotal rocker operatively connected with said valve, and pro-vlded with actuating arms, a ball located adjacent to each of said arms, and having a portion extending into the path of said piston, and means for holding the ball out of contact with the recessed portion of said piston between the inclined shoulders thereof.

2. In a rock drill, the combination with a working cylinder and a piston therein provided with a recessed portion and an inclined actuating shoulder at each end of said recessed portion, of a distributing valve for the cylinder, a pivoted rocker operatively Patented June 11, 1912. a

connected therewith, and provided With actuating arms on opposite sides of the point at the instant of operative contact With said inclined actuating shoulders of the piston.

JAMES MINERS HOLMAN. JOHN LEONARD HOLMAN. Vitnesses to the signature of James Miners Holman: I

A. ALBUTT, M. M. FREEMAN. Y \Vitnesses to the signature of John Leonard Holman:

FREDERICK KIRBY BAKER, WVILLIAM ARTHUR MACLEAN.

Copies of this'patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

